1. Field of the Invention
This invention relates to a process of improving the adhesion of fibrous polymeric aromatic amide reinforcing material to rubber stock and to the products so produced. In particular, this invention relates to a process of improving the adhesion of polymeric aromatic amide fiber, including yarn, fabric and cord, to rubber stock by pretreating the fiber with an aliphatic sulfonylazide and to the vulcanized rubber products so produced.
2. Description of the Prior Art
It is known to reinforce rubber products with various synthetic fibers such as polyester, rayon, nylon, and polymeric aromatic amide. It is also known that polymeric aromatic amide fibers are particularly advantageous reinforcement materials because of their high tensile strength and modulus. Unfortunately, the adhesion of untreated polymeric aromatic amide fibers to rubber stock is low.
It is further known that polysulfonylazides are useful crosslinking agents. For example, U.S. Pat. No. 3,287,376 teaches that aliphatic polysulfonylazides are useful as crosslinking agents for polyolefins. U.S. Pat. No. 3,616,199 and U.S. Pat. No. 3,203,937 teach the use of certain polysulfonylazides as tire cord adhesives. None of these patents suggests in any way the excellent results obtained by using an aliphatic sulfonylazide with a polymeric aromatic amide reinforcing material.